Avoidance of Twinline Towed Array Entanglement

The Program Executive Office of the Littoral and Mine Warfare Systems, Maritime Surveillance Systems Program Office (PMS 485) operates SURTASS T-AGOS ships with TwinLine acoustic surveillance arrays in the Western Pacific where they encounter areas of intense fishing activity. The TwinLine array system consists of two acoustic streamers that are towed by a heavy tow cable and separated by mine-sweeping paravanes on short tethers that pull out and down. The system is susceptible to entanglement by fishing gear which upsets the paravanes and causes collapse of the tow system. This results in a significant degradation in acoustic performance, often damages the tow system, and reduced operational availability. In Phase I, Adaptive Methods (formerly AHA Res., Inc.) developed and tow-tested a prototype TwinLine Separation And Roll Control (SARC) device that replace the paravanes. By design, the SARC is much less likely to become entangled in fishing equipment, and even if entangled it is designed to continue to function, thereby increasing operational availability and minimizing damage to TwinLine towed arrays. In Phase II, Adaptive methods will develop, instrument, and test an EDM and First Article SARC tow body, and develop documentation for its use aboard T-AGOS SWATH tow ships.